public class Main {
    public static String isuperString (String s){
        String sh = "";
        StringBuilder stringBuilder = new StringBuilder();
        for (int i = 0; i < s.length(); i++) {
            char ch = s.charAt(i);
            if(Character.isLetter(ch)){
                if(Character.isUpperCase(ch)){
                    ch = (char)(ch+32);
                }
            }

            stringBuilder.append(ch);
        }
        return stringBuilder.toString();
    }


    public static void main(String[] args) {

        System.out.println(isuperString("ABC"));
    }
}